Field
Systems, apparatuses, methods and example implementations described herein are generally directed to systems for reducing Far-End Crosstalk (FEXT) and, more particularly, to the reduction of FEXT in electrical connectors and plated through holes that are transmitting differential signals.
Related Art
As demand for higher bandwidth continues to grow in telecommunication industry, each device may require more computational power and routing capability. The data rate for each signal channel continues to increase, as does signal density. As a result, unwanted noise, or electromagnetic coupling occurring between neighbor channels significantly increases. For high-speed applicability and reduction in noise compared to single-ended data lines, differential signaling has become a preferred related art method for data transmission.
For the differential victim pair being considered, unwanted electromagnetic coupling (e.g., crosstalk) from neighboring aggressor pairs occurs throughout the data transmission path when at least one of these neighboring pairs is active. When an aggressor's transmitter and victim's receiver are physically far away from each other (located at different chips, for example), crosstalk induced in the same direction as the signal is called far-end crosstalk, or FEXT.
In general, the chip package, connector, and vias are dominant sources of FEXT, due to the close proximity of signal lines. Several attempts at reducing FEXT in the via field on the Printed Circuit Boards (PCBs) have been made by increasing spacing, adding ground between differential pairs, tightening coupling within a differential pair or balancing inductive and capacitive coupling coefficients. In an example related art implementation, two adjacent pairs of vias are made symmetric and equi-distanced to reduce the FEXT of the via itself.
However, such related attempts have increased consumption of allocated real estate, imposed difficulty in design and implementation, and been relatively insufficient in reducing cumulative total FEXT, particularly in higher frequency systems. Therefore, there is a need for additional ways to reduce total FEXT.